This study will recruit 20 children with idiopathic ASD (defined by DSM-IV criteria) and 20 age- and gender-matched controls with typical neuropsychological developmental patterns. The number of subjects necessary for this study was determined by power analysis. Using a two sample t-test model with 15 ASD and 15 control subjects in each group would have 80% power to detect changes in expression equal to twice the standard deviation of the group mean with Bonferonni corrected level (p<0.0001) based on expectations of measuring 500 miRNA in each sample (Lenth, 2006).